Optical waveguide bodies and luminaires utilizing same

ABSTRACT

A luminaire comprises an optical element. The optical element comprises a coupling portion that comprises a coupling cavity that extends along a length of the optical element. The coupling cavity is configured to receive at least one light emitting diode. The optical element further comprises first and second sections extending away from the coupling portion of the optical element along the length of the coupling cavity. The first section comprises a first thickness closer to the coupling portion and a second thickness further from the coupling portion. The first thickness is greater than the second thickness. The second section comprises a third thickness closer to the coupling portion and a fourth thickness further from the coupling portion. The third thickness is greater than the fourth thickness. Light is extracted out of extraction features of opposing sides of at least one section.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/991,581, filed Jan. 8, 2016, entitled “OpticalWaveguide Bodies and Luminaires Utilizing Same”, now patented as U.S.Pat. No. 9,625,636, which is a divisional application of U.S. patentapplication Ser. No. 14/577,730, filed Dec. 19, 2014, entitled “OpticalWaveguide Bodies and Luminaires Utilizing Same”, now abandoned. SaidU.S. patent application Ser. No. 14/991,581, filed Jan. 8, 2016,entitled “Optical Waveguide Bodies and Luminaires Utilizing Same”further comprises a continuation-in-part of U.S. patent application Ser.No. 14/015,801, filed Aug. 30, 2013, entitled “Consolidated Troffer”,now patented as U.S. Pat. No. 9,291,320, and further comprises acontinuation-in-part of U.S. patent application Ser. No. 13/842,521,filed Mar. 15, 2013, entitled “Optical Waveguides”, now patented as U.S.Pat. No. 9,519,095, and further comprises a continuation-in-part of U.S.patent application Ser. No. 13/839,949, filed Mar. 15, 2013, entitled“Optical Waveguide and Lamp Including Same”, now patented as U.S. Pat.No. 9,581,751, and further comprises a continuation-in-part of U.S.patent application Ser. No. 13/841,074, filed Mar. 15, 2013, entitled“Optical Waveguide Body”, now patented as U.S. Pat. No. 9,625,638, andfurther comprises a continuation-in-part of U.S. application Ser. No.13/841,622, filed Mar. 15, 2013, entitled “Shaped Optical WaveguideBodies”, now abandoned, and further comprises a continuation-in-part ofU.S. patent application Ser. No. 13/840,563, filed Mar. 15, 2013,entitled “Optical Waveguide and Luminaire Incorporating Same”, andfurther comprises a continuation-in-part of U.S. patent application Ser.No. 13/938,877, filed Jul. 10, 2013, entitled “Optical Waveguide andLuminaire Incorporating Same”, now patented as U.S. Pat. No. 9,389,367,and further comprises a continuation-in-part of U.S. patent applicationSer. No. 14/101,099, filed Dec. 9, 2013, entitled “Optical WaveguideAssembly and Light Engine Including Same”, now patented as U.S. Pat. No.9,411,086, and further comprises a continuation-in-part of U.S. patentapplication Ser. No. 14/101,129, filed Dec. 9, 2013, entitled“Simplified Low Profile Module With Light Guide For Pendant, SurfaceMount, Wall Mount and Stand Alone Luminaires”, and further comprises acontinuation-in-part of U.S. patent application Ser. No. 14/101,051,filed Dec. 9, 2013, entitled “Optical Waveguide and Lamp IncludingSame”, now patented as U.S. Pat. No. 9,366,396, and further comprises acontinuation-in-part of International Application No. PCT/US14/13931,filed Jan. 30, 2014, entitled “Optical Waveguides and LuminairesIncorporating Same”, now expired, and further comprises acontinuation-in-part of International Application No. PCTIUS14/13937,filed Jan. 30, 2014, entitled “Optical Waveguide Bodies and LuminairesUtilizing Same”, now expired, and further comprises acontinuation-in-part of International Application No. PCTIUS14/30017,filed Mar. 15, 2014, entitled “Optical Waveguide Body”, now expired, andfurther comprises a continuation-in-part of U.S. patent application Ser.No. 14/292,778, filed May 30, 2014, entitled “Optical Waveguide Bodiesand Luminaires Utilizing Same”, now patented as U.S. Pat. No. 9,366,799,and further comprises a continuation-in-part of U.S. patent applicationSer. No. 14/485,609, filed Sep. 12, 2014, entitled “Luminaire UtilizingWaveguide”, now patented as U.S. Pat. No. 9,952,372, and furthercomprises a continuation-in-part of U.S. patent application Ser. No.14/462,426, filed Aug. 18, 2014, entitled “Outdoor and/or Enclosed LEDLuminaire for General Illumination Applications, Such as Parking Lotsand Structures”, which claims the benefit of U.S. Provisional PatentApplication No. 61/922,017, filed Dec. 30, 2013, entitled “OpticalWaveguide Bodies and Luminaires Utilizing Same”, now expired, andfurther claims the benefit of U.S. Provisional Patent Application No.62/005,955, filed May 30, 2014, entitled “Parking Structure LED Light”,now expired, and further claims the benefit of U.S. Provisional PatentApplication No. 62/009,039, filed Jun. 6, 2014, entitled “ParkingStructure LED Light”, now expired. Said U.S. patent application Ser. No.14/991,581, filed Jan. 8, 2016, entitled “Optical Waveguide Bodies andLuminaires Utilizing Same”, now patented as U.S. Pat. No. 9,625,636,further comprises a continuation-in-part of U.S. patent application Ser.No. 14/462,391, filed Aug. 18, 2014, entitled “Optical Components forLuminaire”, now patented as U.S. Pat. No. 9,513,424, and furthercomprises a continuation-in-part of U.S. patent application Ser. No.14/472,035, filed Aug. 28, 2014, entitled “Luminaires Utilizing EdgeCoupling”, now patented as U.S. Pat. No. 9,645,303. All of theabove-mentioned applications are owned by the assignee of the presentapplication. The disclosures of all of the abovementioned applicationsare incorporated by reference herein.

REFERENCE REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

SEQUENTIAL LISTING

Not applicable

FIELD OF DISCLOSURE

The present subject matter relates to luminaires, and more particularlyto luminaires utilizing optical waveguides for general lighting.

BACKGROUND

An optical waveguide mixes and directs light emitted by one or morelight sources, such as one or more light emitting diodes (LEDs). Atypical optical waveguide includes three main components: one or morecoupling elements, one or more distribution elements, and one or moreextraction elements. The coupling component(s) direct light into thedistribution element(s), and condition the light to interact with thesubsequent components. The one or more distribution elements control howlight flows through the waveguide and are dependent on the waveguidegeometry and material. The extraction element(s) determine how light isremoved by controlling where and in what direction the light exits thewaveguide.

When designing coupling component(s), the primary considerations are:maximizing the efficiency of light transfer from the source into thewaveguide; controlling the location of light injected into thewaveguide; and controlling the angular distribution of the light in thecoupling optic. Light may be coupled into the waveguide through an airgap and a coupling cavity defined by surfaces located at an edge and/orinterior portions of the waveguide. Such surfaces comprise an interfacebetween the relatively low index of refraction of air and the relativelyhigh index of refraction of the waveguide material. One way ofcontrolling the spatial and angular spread of injected light is byfitting each source with a dedicated lens. These lenses can be disposedwith an air gap between the lens and the coupling optic, or may bemanufactured from the same piece of material that defines thewaveguide's distribution element(s).

After light has been coupled into the waveguide, it must be guided andconditioned to the locations of extraction. The simplest example is afiber-optic cable, which is designed to transport light from one end ofthe cable to another with minimal loss in between. To achieve this,fiber optic cables are only gradually curved and sharp bends in thewaveguide are avoided. In accordance with well-known principles of totalinternal reflectance light traveling through a waveguide is reflectedback into the waveguide from an outer surface thereof, provided that theincident light does not exceed a critical angle with respect to thesurface.

In order for an extraction element to remove light from the waveguide,the light must first contact the feature comprising the element. Byappropriately shaping the waveguide surfaces, one can control the flowof light across the extraction feature(s). Specifically, selecting thespacing, shape, and other characteristic(s) of the extraction featuresaffects the appearance of the waveguide, its resulting distribution, andefficiency.

Hulse U.S. Pat. No. 5,812,714 discloses a waveguide bend elementconfigured to change a direction of travel of light from a firstdirection to a second direction. The waveguide bend element includes acollector element that collects light emitted from a light source anddirects the light into an input face of the waveguide bend element.Light entering the bend element is reflected internally along an outersurface and exits the element at an output face. The outer surfacecomprises beveled angular surfaces or a curved surface oriented suchthat most of the light entering the bend element is internally reflecteduntil the light reaches the output face

Parker et al. U.S. Pat. No. 5,613,751 discloses a light emitting panelassembly that comprises a transparent light emitting panel having alight input surface, a light transition area, and one or more lightsources. Light sources are preferably embedded or bonded in the lighttransition area to eliminate any air gaps, thus reducing light loss andmaximizing the emitted light. The light transition area may includereflective and/or refractive surfaces around and behind each lightsource to reflect and/or refract and focus the light more efficientlythrough the light transition area into the light input surface of thelight-emitting panel. A pattern of light extracting deformities, or anychange in the shape or geometry of the panel surface, and/or coatingthat causes a portion of the light to be emitted, may be provided on oneor both sides of the panel members. A variable pattern of deformitiesmay break up the light rays such that the internal angle of reflectionof a portion of the light rays will be great enough to cause the lightrays either to be emitted out of the panel or reflected back through thepanel and emitted out of the other side.

Shipman, U.S. Pat. No. 3,532,871 discloses a combination running lightreflector having two light sources, each of which, when illuminated,develops light that is directed onto a polished surface of a projection.The light is reflected onto a cone-shaped reflector. The light istransversely reflected into a main body and impinges on prisms thatdirect the light out of the main body.

Simon U.S. Pat. No. 5,897,201 discloses various embodiments ofarchitectural lighting that is distributed from contained radiallycollimated light. A quasi-point source develops light that is collimatedin a radially outward direction and exit means of distribution opticsdirect the collimated light out of the optics.

A.L.P. Lighting Components, Inc. of Niles, Ill., manufactures awaveguide having a wedge shape with a thick end, a narrow end, and twomain faces therebetween. Pyramid-shaped extraction features are formedon both main faces. The wedge waveguide is used as an exit sign suchthat the thick end of the sign is positioned adjacent a ceiling and thenarrow end extends downwardly. Light enters the waveguide at the thickend and is directed down and away from the waveguide by thepyramid-shaped extraction features.

Low-profile LED-based luminaires have recently been developed (e.g.,General Electric's ET series panel troffers) that utilize a string ofLED components directed into the edge of a waveguiding element (an“edge-lit” approach). However, such luminaires typically suffer from lowefficiency due to losses inherent in coupling light emitted from apredominantly lambertian emitting source such as a LED component intothe narrow edge of a waveguide plane.

SUMMARY

According to one aspect, a luminaire comprises an optical element. Theoptical element comprises a coupling portion that comprises a couplingcavity that extends along a length of the optical element. The couplingcavity is configured to receive at least one light emitting diode. Theoptical element further comprises first and second sections extendingaway from the coupling portion of the optical element along the lengthof the coupling cavity. The first section comprises a first thicknesscloser to the coupling portion and a second thickness further from thecoupling portion. The first thickness is greater than the secondthickness. The second section comprises a third thickness closer to thecoupling portion and a fourth thickness further from the couplingportion. The third thickness is greater than the fourth thickness. Lightis extracted out of extraction features of opposing sides of at leastone section.

According to another aspect, a waveguide body comprises a length from afirst end to a second end along a longitudinal axis. The waveguide bodyfurther comprises a coupling portion that comprises first and secondcoupling surfaces defining at least in part an elongate coupling cavity.The waveguide body further comprises first and second opposed sectionsextending along the length of the waveguide body. Said first and secondopposed sections further comprise respective first and second lowersurfaces disposed at different first and second side section angles withrespect to a first axis lying in a plane normal to the longitudinalaxis. The first axis bisects the coupling portion. The first sectioncomprises a first thickness proximal the coupling portion and a secondthickness smaller than the first thickness and disposed distal from thecoupling portion. The second section comprises a third thicknessproximal the coupling portion and a fourth thickness smaller than thethird thickness and disposed distal from the coupling portion.

Other aspects and advantages will become apparent upon consideration ofthe following detailed description and the attached drawings whereinlike numerals designate like structures throughout the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view showing an embodiment of a disclosedluminaire.

FIG. 2 is a combined end elevation view and block diagram of theembodiment of FIG. 1.

FIG. 2A is an exploded isometric view of the luminaire of FIGS. 1 and 2.

FIG. 3 is an enlarged, fragmentary side elevational view of the centralsection as referenced by the view lines 3-3 of FIG. 2.

FIG. 3A is an enlarged, fragmentary side elevation of a central section.

FIG. 3B is an enlarged, fragmentary side elevation of a luminaire thatgenerates two independent light beams.

FIG. 4 is an enlarged, fragmentary side elevational view of anextraction feature as referenced by the view line 4-4 of FIG. 2.

FIG. 4A is a graph illustrating a desired light distribution emittedfrom the luminaire of FIGS. 1 and 2.

FIG. 4B is fragmentary view of an extraction feature used in oneembodiment of the disclosure.

FIG. 4C is a fragmentary view of an extraction feature used in a secondembodiment of the disclosure.

FIG. 4D is a fragmentary isometric view of a waveguide surface showing aparticular embodiment of extraction features extending outwardly fromthe surface of the waveguide.

FIG. 4E is fragmentary view of an extraction feature used in a furtherembodiment of the disclosure.

FIG. 4F is an enlarged, fragmentary, cross sectional view of theextraction feature of FIG. 4E.

FIG. 4G is a fragmentary view of an extraction feature used in a furtherembodiment of the disclosure.

FIG. 4H is an enlarged plan view of the extraction feature of FIG. 4G.

FIG. 4I is an enlarged, fragmentary, cross sectional view of theextraction feature of FIG. 4G.

FIG. 4J is a graph illustrating an alternative desired lightdistribution emitted from the luminaire of FIGS. 1 and 2.

FIG. 5A is a perspective of a further embodiment of a luminaire.

FIG. 5B is an end elevational view of a luminaire that is a modifiedversion of that shown in FIG. 5A with an end cap removed.

FIG. 5C is an enlarged, fragmentary side elevational view of the centralsection of the waveguide body of FIG. 5B.

FIG. 6 is an enlarged, fragmentary cross sectional view of a centralsection of any of the waveguide bodies described herein showing a lightsource located proximal the central section and a mirrored top reflectoropposite the light source.

FIG. 6A is an enlarged, fragmentary end view of a central sectionshowing a specular reflective body located in the V-shaped convergencebetween the first and second sides of the waveguide body.

FIG. 7 is a diagram showing light rays traveling through a waveguidebody having facets disposed at a first angle.

FIG. 8 is a diagram showing light rays traveling through a waveguidehaving facets disposed a second angle shallower than the facets of FIG.7.

FIG. 9 is a diagram showing light rays traveling through the waveguidebody in another embodiment of a disclosed luminaire.

FIG. 10 is side elevational view of a waveguide used in yet anotherembodiment of a disclosed luminaire.

FIG. 11 is an end elevational view of a waveguide body useable in astill further embodiment of a luminaire.

FIG. 12 is an isometric view of the waveguide body of FIG. 11.

FIG. 13A is an end elevational view of another waveguide body usable inyet another embodiment a disclosed luminaire.

FIG. 13B is an isometric view of the waveguide body of FIG. 13A.

FIG. 14A is an end elevational view of a waveguide body usable in astill further embodiment of a luminaire.

FIG. 14B is an isometric view of the waveguide body of FIG. 14A.

FIG. 15A is an end elevational view of a waveguide body usable inanother embodiment of a luminaire.

FIG. 15B is an isometric view of the waveguide body of FIG. 15A.

FIG. 16A is an isometric view of yet another waveguide body usable in astill further embodiment of a luminaire.

FIG. 16B is an isometric view of a still further waveguide body useablein another embodiment of a luminaire.

FIG. 17A is an isometric view of yet another waveguide body usable in astill further embodiment of a luminaire.

FIG. 17B is an isometric view of a still further waveguide body useablein another embodiment of a luminaire.

FIG. 18A is an isometric view of yet another waveguide body usable in astill further embodiment of a luminaire.

FIG. 18B is an isometric view of a still further waveguide body useablein another embodiment of a luminaire.

FIG. 19A is an isometric view of yet another waveguide body usable in astill further embodiment of a luminaire.

FIG. 19B is an isometric view of a still further waveguide body useablein another embodiment of a luminaire.

FIG. 20 is an end view of an embodiment of a luminaire.

FIG. 21 is a side elevation view of an embodiment of a central sectionof a waveguide disclosed in the application.

FIG. 22A is a fragmentary isometric of an embodiment of extractionfeatures used in conjunction with the waveguide disclosed in theapplication.

FIG. 22B is a fragmentary isometric of a second embodiment of extractionfeatures used in conjunction with the waveguide disclosed in theapplication.

FIG. 22C is a fragmentary isometric of still another embodiment ofextraction features used in conjunction with the waveguide disclosed inthe application.

FIG. 22D is an enlarged, fragmentary, cross sectional view of a furtherembodiment of extraction features used in conjunction with the waveguidedisclosed in the application.

FIG. 23A is an isometric view of yet another waveguide body usable in afurther embodiment of a luminaire.

FIG. 23B is a second isometric view of the waveguide body shown in FIG.23A.

FIG. 23C is a side elevation of the waveguide body shown in FIG. 23A.

FIG. 24A is a lower elevation view of still another embodiment of adisclosed luminaire.

FIG. 24B is a sectional view of the luminaire shown in FIG. 24A.

FIG. 24C is an isometric view of the luminaire shown in FIG. 24A.

FIG. 25A is a lower elevation view of yet another embodiment of adisclosed luminaire.

FIG. 25B is a side elevation of the luminaire shown in FIG. 25A.

FIG. 25C is a side elevation of one of the components of the luminaireshown in FIG. 25A.

FIG. 25D is an isometric view showing in dash lines the outline of oneof the components of the luminaire shown in FIG. 25A and in solid linethe cross section of the component.

FIG. 26 is a side elevation view of an embodiment of a central sectionof a waveguide disclosed in the application showing a textured surfaceopposite the input surface.

FIG. 27 is a side elevation view of an embodiment of a luminairedisclosed in the application and a reflector opposite one side of theluminaire.

FIG. 27A is a graph illustrating an alternative desired lightdistribution emitted from the luminaire of FIG. 27.

FIG. 28 is a side elevation view of another embodiment of a waveguidebody.

FIG. 28A is an exploded isometric view of the embodiment of FIG. 28.

FIG. 29 is a side elevation view of another embodiment of a waveguidebody.

FIG. 30 is a further embodiment of a waveguide used in yet anotherembodiment of a disclosed luminaire.

FIG. 30A is a side elevation view of a central section of the embodimentof FIG. 30.

FIG. 31 is an isometric view of yet another embodiment of a luminaire.

FIG. 32 is a side elevation view of the embodiment of FIG. 31.

FIG. 33 is an end elevation view of the embodiment of FIG. 31.

FIG. 34 is a bottom elevation view of one of the luminaire sections ofthe embodiment of FIG. 31.

FIG. 35 is a right end view of the luminaire section of FIG. 34 with anend cap omitted therefrom.

FIG. 36 is a left end view of the luminaire section of FIG. 34 with anend cap omitted therefrom.

FIG. 37 is a sectional view taken generally along the lines 37-37 ofFIG. 34.

FIG. 38 is an enlarged fragmentary view illustrating the structure ofFIG. 37 in greater detail.

FIG. 38A is an enlarged fragmentary sectional view taken generally alongthe lines 38A-38A of FIG. 34.

FIG. 39 is an exploded isometric view of the luminaire section of FIG.34.

FIG. 39A is an enlarged isometric view of the clamping plate of FIG. 39.

FIGS. 40-42 are isometric views illustrating a sequence of steps toassemble luminaire sections.

FIGS. 43 and 44 are sectional views taken generally along the lines43-43 of FIG. 42 before and after tightening of the clamping fasteners,respectively.

DETAILED DESCRIPTION

The following examples further illustrate the invention but, of course,should not be construed as in any way limiting its scope.

In general, the curvature and/or other shape of a waveguide body and/orthe shape, size, and/or spacing of extraction features determine theparticular light extraction distribution. All of these options affectthe visual uniformity from one end of the waveguide to another. Forexample, a waveguide body having smooth surfaces may emit light atcurved portions thereof. The sharper the curve is the more light isextracted. The extraction of light along a curve also depends on thethickness of the waveguide body. Light can travel through tight curvesof a thin waveguide body without reaching the critical angle, whereaslight that travels through a thick waveguide body is more likely tostrike the surface at an angle that allows the light to escape.According to well-known TIR principles, the light rays of the groups 91a, 91 b continue to travel through the arm portions 62, 64,respectively, until such rays strike an index interface surface at aparticular angle less than an angle measured with respect to a linenormal to the surface point at which the light rays are incident (or,equivalently, until the light rays exceed an angle measured with respectto a line tangent to the surface point at which the light ray isincident) and the light rays escape, as seen in FIGS. 7 and 8.

Tapering a waveguide body causes light to reflect internally along thelength of the waveguide body while increasing the angle of incidence.Eventually, this light strikes one side at an angle that allows thelight to escape. The opposite example, i.e., a gradually thickeningwaveguide body over the length thereof, causes light to collimate alongthe length with fewer and fewer interactions with the waveguide bodysurfaces. These reactions can be used to extract and control lightwithin the waveguide. When combined with dedicated extraction features,tapering allows one to change the incident angular distribution acrossan array of features. This, in turn, controls how much, and in whatdirection light is extracted. Thus, a select combination of curves,tapered surfaces, and extraction features can achieve a desiredillumination and appearance.

Still further, the waveguide bodies contemplated herein are made of anysuitable optically transmissive material, such as an acrylic material, asilicone, a polycarbonate, a glass material, a cyclic olefin copolymer,air, or other suitable material(s), or combinations thereof to achieve adesired effect and/or appearance.

According to one aspect, a waveguide directs light into at least one upto an infinite number of beams or ray groups, wherein the rays of eachgroup travel through the waveguide within a range of angles relative toone another. Each range may be narrow or broad within the TIR limits ofthe waveguide material.

According to another aspect, a waveguide arranges light into a pluralityof groups that bounce at least once inside the waveguide by totalinternal reflection (“TIR”) off one or more surfaces of the waveguide.Each group comprises a plurality of light rays that travel at anglesthat are disposed within a narrow or broad range of angles relative toone another.

In any embodiment, the range may be so narrow that the light rays of raygroup may be considered to be fully collimated, or nearly so, or therange may be so broad that the light rays of a ray group may beconsidered to be anti-collimated, or nearly so. Controlling the rayangles in this manner can lead to increased light control, reducedwaveguide size and weight, and reduced luminaire costs.

FIGS. 1-3 show a luminaire 10 comprising a waveguide having a waveguidebody 12 including a central section 18 and first and second separateside sections 20, 22 extending away from the central section 18 alongfirst and second directions, respectively, and terminating at first andsecond outer ends 20A, 22A, respectively (FIG. 2). The side sections 20,22 in the illustrated embodiment are preferably mirror images of oneanother. The central section 18 includes a coupling portion 24, and alight source 25 in the form of one or more LED element(s) 26 aredisposed adjacent the coupling portion 24, as shown in FIG. 2, and thelight source 25 is adapted to produce light that is directed into thewaveguide body 12 via the coupling portion 24. A power circuit C (FIG.2) provides power to the light source 25, and the waveguide body 12includes a plurality of light extraction features 14 (FIGS. 4, 4B, 4C,4D, 4E, and 4G show various embodiments of such features 14) thatextract light out of the side sections 20, 22, for example as shown inFIGS. 7 and 8.

More specifically, as seen in FIG. 2A, the luminaire 10 includes a baseelement in the form of a substrate 27 having a base surface 28. Ifdesired, the base surface 28 may be covered or coated by a reflectivematerial, which may be a white material or a material that exhibitsspecular reflective characteristics. LED elements 26 are mounted on thebase surface 28. The substrate 27 is secured in fixed relation to thewaveguide body 12 in any suitable fashion such that the LED elements arepreferably equally spaced along a longitudinal axis L (FIG. 2A) andfurther extend into a cavity 29 (FIG. 3) of the coupling portion 24.Each LED element 26 may be a single white LED or multiple white LEDs oreach may comprise multiple LEDs either mounted separately or together ona single substrate or package including a phosphor-coated LED eitheralone or in combination with a color LED, such as a green LED, etc. Inthose cases where a soft white illumination is to be produced, each LEDelement 26 typically includes one or more blue shifted yellow LEDs andone or more red LEDs. Different color temperatures and appearances couldbe produced using other LED combinations, as is known in the art. In oneembodiment, the light source comprises any LED, for example, an MT-G LEDmodule incorporating TrueWhite® LED technology or as disclosed in U.S.patent application Ser. No. 13/649,067, filed Oct. 10, 2012, entitled“LED Package with Multiple Element Light Source and Encapsulant HavingPlanar Surfaces” by Lowes et al., the disclosure of which is herebyincorporated by reference herein, both as developed by Cree, Inc., theassignee of the present application. In any of the embodiments disclosedherein the LED(s) have a particular emission distribution, as necessaryor desirable. For example, a side emitting LED disclosed in U.S. Pat.No. 8,541,795, the disclosure of which is incorporated by referenceherein, may be utilized inside the waveguide body. More generally, anylambertian, symmetric, wide angle, preferential-sided, or asymmetricbeam pattern LED(s) may be used as the light source. Still further, anyof the LED arrangements and optical elements disclosed in co-pendingU.S. patent application Ser. No. 14/101,147, filed Dec. 9, 2013,entitled “Luminaires Using Waveguide Bodies and Optical Elements” byKeller et al., incorporated by reference herein, may be used.

The power circuit C may be disposed on the substrate 27 or may belocated remotely, or a portion of the power circuit C may be disposed onthe substrate and the remainder of the power circuit C may be remotelylocated. In any event, the power circuit C is designed to operate thelight source 25 with AC or DC power in a desired fashion to producelight of a desired intensity and appearance. If necessary or desirable,a heat exchanger (not shown) is arranged to dissipate heat and eliminatethermal crosstalk between the LEDs and the power circuit C. Preferably,the light source 25 develops light appropriate for general illuminationpurposes including light that may be generated in a down light, a lightthat produces a wall washing effect, a task light, a troffer, or thelike. The power circuit C may include a buck regulator, a boostregulator, a buck-boost regulator, a SEPIC power supply, or the like,and is used in any of the embodiments disclosed herein and may comprisea driver circuit as disclosed in U.S. patent application Ser. No.14/291,829, filed May 30, 2014, entitled “High Efficiency Driver Circuitwith Fast Response” by Hu et al. or U.S. patent application Ser. No.14/292,001, filed May 30, 2014, entitled “SEPIC Driver Circuit with LowInput Current Ripple” by Hu et al. incorporated by reference herein. Thecircuit C may further be used with light control circuitry LC thatcontrols color temperature of any of the embodiments disclosed herein inaccordance with user input such as disclosed in U.S. patent applicationSer. No. 14/292,286, filed May 30, 2014, entitled “Lighting FixtureProviding Variable CCT” by Pope et al. incorporated by reference herein.

In the embodiment of FIGS. 1-3 each of the first and the second sidesections 20, 22 has an upper and a lower surface 30, 32 and includes afirst end 20B, 22B proximal to the coupling portion 24 and a second end20A, 22A, respectively, distal to the coupling portion 24. The first end20B, 22B has a first thickness T₁, the second end 20A, 22A has a secondthickness T₂, and the first thickness T₁ is greater than the secondthickness T₂, and hence, the side sections 20, 22 are tapered. In aparticular embodiment, for example, the first thickness T₁ is no greaterthan about 6 millimeters and the second thickness is no less than about2 millimeters. In an embodiment, a center portion of each of the firstand the second side sections 20, 22 also has a thickness equal to thesecond end 20A, 22A in that, for example, it is no less than about 2millimeters. It should be noted that the minimum thickness is onlylimited by structural strength considerations, while maximum thicknessis currently only limited by manufacturing considerations. In anembodiment, the ratio of the maximum to minimum thickness of thewaveguide body is 10:1 or less. In a more particular version of theembodiment, the ratio is about approximately 3:1. In a particularembodiment, as shown in FIG. 27, a reflector 53 may be placed above theupper surface 30 of the waveguide 12. If desired, the reflector 53 canbe replaced by a specular or reflective coating disposed on the surface30. (In the embodiment of FIG. 27, the surface 32 is disposed above thesurface 30, opposite to previous illustrated embodiments.) FIG. 27Aillustrates an example light distribution of the embodiment of FIG. 27,where the concentric circles mark the magnitude of intensity (candelas:lumens/steradian), and the lines extending radially from the center markthe angle of the exiting light with 0° pointing straight down, 90° tothe right and 180° straight up. Other desired light distributions may berealized.

In still another embodiment, a flat waveguide body 12 is used in whichthe first thickness T₁ is equal to the second thickness T₂, as shown inFIG. 5B.

Also in the illustrated embodiment of FIGS. 1-3, the coupling portion 24curves upward away from the LED elements 26 toward one or both of thesecond ends 20A, 22A. The upper surface 30 of the first and secondsections 20, 22 may be textured. Each textured surface 30 may comprise aplurality of light extraction features 14, one of which is shown in FIG.4. In a more particular embodiment, each of the plurality of lightextraction features 14 comprises an intermediate surface 40 that extendsfrom a first surface 38 to a second surface 42. All or some of theintermediate surfaces 40 may be planar or curved, as shown in FIGS. 4,4B, 4C, 4D, 4E, 4G, 4H, and 4I. In an embodiment, the angle of curvatureof the intermediate surface 40 may range from 10° to 80°. In a moreparticular version of the embodiment, the angle of curvature is aboutapproximately 30° to 60°. In still another version of the embodiment,the angle of curvature of the intermediate surface 40 is approximately42.5° to 50°. The intermediate surfaces 40 may, but need not, have aconstant radius of curvature. Furthermore, the edges 47 of the couplingportion 24 can be of any shape including, but not limited to, planarcurved, angled, tapered, etc.

Also preferably, each first surface 38 is displaced from an associatedadjacent second surface 42 by a particular distance D1, as shown in FIG.4, wherein the distances D₁ are constant or vary along the length andwidth of each surface 30. The disposition of the center of the radius ofcurvature, the magnitude of the radius of curvature, and the arcuateextent of each intermediate surface 40 affect the distribution of lightfrom the waveguide body 12. In another embodiment, as seen in FIGS. 7and 8, the intermediate surfaces 40 are planar, and the intermediatesurfaces 40 are all parallel to one another, although the surfaces 40need not all be planar or parallel. In an embodiment, the perpendiculardistance between the first surface 38 and the adjacent second surface 42(i.e., the length of a line extending from and normal to the surface 38to an imaginary projection of the plane 42 below the surface 38) ispreferably less than 100 microns, and more preferably between about 20and about 100 microns. In another embodiment, the intermediate surfaces40 are parallel to one another and are disposed at non-zero angles withrespect to associated first and second surfaces 38, 40. The anglebetween each intermediate surface 40 and a line tangent to an adjacentassociated surface 38 or 42 where the surface 38 or 42 meets the surface40 may be relatively steep (for example, as seen in FIG. 7) or may berelatively shallow (e.g., as seen in FIG. 8). Thus, for instance, theangle between each intermediate surface 40 and a line tangent to anadjacent associated surface 38 where the surface 38 meets the surface 40may be in a range between about 5 degrees and 90 degrees, and moreparticularly, may be between about 40 degrees and about 60 degrees, and,most preferably, about 50 degrees. This angle (or any other relatedangle, such as the angle between the intermediate surface 40 and a linetangent to an adjacent associated surface 42 where the surface 42 meetsthe surface 40) and the size of each intermediate surface 40 affect theoutput distribution of light from the waveguide body 12.

It should also be noted that the extraction features may be of differingsize, shape, and/or spacing over the surface(s) of the waveguide body 12so that an asymmetric emitted light distribution is obtained. Forexample, the extraction features may include a combined notch and stepextraction that leads to a tapered edge, as shown in FIGS. 22A-22D. Theextraction features shown in FIG. 22D may have dimensions noted in thefollowing table, although such dimensions are exemplary only and notlimiting.

TABLE 1 NOMINAL DIMENSION (Millimeters - unless FIG. 22D otherwisespecified) Q 0.100 R 0.134 S 20 degrees T 65 degrees U 0.020 V 0.020 W0.092 X 30 degrees Y 50 degrees Z 0.060 AA 0.140

Additionally, as seen in co-pending U.S. patent application Ser. No.14/101,086, filed Dec. 9, 2013, entitled “Optical Waveguides andLuminaires Incorporating Same” by Keller et al., the extraction featuresmay comprise small indents or protrusions and a relatively large numberof such extraction features may be disposed to the left of the couplingportion 24 and a relatively small number of such extraction features maybe disposed to the right of the coupling portion 24. In such anembodiment, as should be evident, more light is extracted from the leftside of the waveguide body 12 and relatively less light is extractedfrom the right side of the waveguide body 12.

In another embodiment, the lower surface 32 is textured. This texturingmay be effected by a roughened surface that creates a diffusion effect,and/or by a plurality of extraction features 14. These extractionfeatures 14 may be identical or similar to those described above.

Referring again to FIGS. 2 and 2A, in the illustrated embodiment, thewaveguide body 12 has a length L₁ parallel to the longitudinal axis L,the waveguide body 12 further has a width W transverse to the length L₁.The width W can be as little about 3 inches or as wide as manufacturingallows. In one embodiment, the width W is about 12 inches and in anotherembodiment the width W is about 24 inches. The length L₁ can be aslittle as about 2 inches or as long as manufacturing allows. In anembodiment, the length L₁ is preferably at least about 12 inches, and,more preferably, at least about 48 inches. In the embodiment shown inFIG. 2, the waveguide disclosed herein may have the dimensions noted inthe following table. It should be noted that the dimensions in thefollowing table as exemplary only and not limiting:

TABLE 2 NOMINAL DIMENSION (Millimeters - unless FIG. 2 otherwisespecified) A 2.0 B 3.2 C 3.0 D 7.6 E 2.0 F 10 degrees G 300

As shown in FIG. 3, the coupling portion 24 has a concave first surface44 defining the cavity 29 and a curved V-shaped second surface 46disposed opposite the concave first surface 44. The concave surface 44may be textured so as to allow for better color mixing of the light, asshown in FIG. 26. In one embodiment, the V-shaped second surface 46 issmooth and uncoated. In an alternative embodiment seen in FIG. 6, anoptional layer of specular material 48 is disposed on the V-shapedsecond surface 46. In still another version of the embodiment seen inFIG. 6A, an optional specular reflective body 49 is located in theV-shaped convergence between the first and second sides 20, 22. Thematerial 48 or the body 49 may be used in any of the embodimentsdiscussed herein.

While redirecting rays of a light source 26 into one or more ray groupsor beams each having a ray angle distribution range typically requiresan optic substantially larger than the light source, such redirectioncan also be accomplished by using a thick waveguide 12, as shown in FIG.3A. However, it may be preferable for costs reasons to undertake suchlight redirection using a relatively thin waveguide. For example, asseen in FIG. 3B, light developed by the light source 26 can beredirected into two independent sets of light rays. Each set of rayshave a very narrow distribution range or may be substantially or fullycollimated in order to achieve the desired light distribution out of thewaveguide 12. Specifically, and with reference to FIG. 6, the primarilylambertian distribution of light developed by the LED element(s) 26 isincident on the walls defining the concave surface 44, and lightincident on an upper surface 44 a travels through the coupling portion24 and strikes the curved V-shaped second surface 46. The surfaces 46 a,46 b that make up the second surface 46 redirect the light by TIR(and/or specular reflection if the material 48 on the body 49 ispresent) into the sides 20, 22 as first sets of ray groups 51 a, 51 bthat bounce due to total internal reflection between the upper and lowersurfaces 30, 32 until such rays exceed the critical angle of thematerial of the waveguide body 12 and escape, as seen in FIGS. 7-9.Light incident on lower surfaces 44 b of the concave surface 44 travelsthrough the coupling portion 24 directly into the portions 20, 22without striking the curved V-shaped second surface 46. In theembodiment of FIG. 3B the lower surfaces 44 b are curved in a mannerthat causes the light passing through the surfaces 44 b to be redirectedsecond sets of ray groups 52 a, 52 b. This light also bounces betweenthe upper and lower surfaces 30, 32 until such rays exceed the criticalangle of the material of the waveguide body 12 and escape, as also seenin FIGS. 7-9. In the illustrated embodiment of FIG. 3B, the ray groups51 a, 51 b, 52 a, and 52 b have narrow ray angle distributions (i.e.,the ray groups are substantially or fully collimated). In someembodiments, the surfaces 46 a, 46 b may be parabolic in shape andcentered on the light source 26. The extraction features 14 cause thelight to exit the waveguide 12 in a controlled fashion such that lightis directed out of the upper and lower surfaces 30, 32. Because thelight rays are at least substantially collimated they experience minimalspreading as they propagate through the waveguide body 12. This resultsin highly controlled beams which can be either extracted in a collimatedfashion, or spread into a wide distribution.

Specifically, as shown in FIGS. 6-8, the collimated light raysrepeatedly bounce through the guide 12 by total internal reflectionuntil they strike an extraction feature 14 and are redirected into thewaveguide 12 or escape into the space or room to be illuminated. Thelight that strikes the extraction features 14 and is reflected back intothe waveguide body 12 may strike the opposing waveguide body surface andescape out of the waveguide body 12 or may further reflect off theopposing surface and continue to travel within the waveguide body 12,depending upon the incident angle of the light striking such opposingsurface. The light eventually leaves the waveguide body 12, preferablybefore reaching outer ends 20A, 22A. This escape is facilitated by theextraction features 14 which have stepped surfaces parallel to oneanother. This arrangement gives a tapered appearance to side sections20, 22. The extracted light may have the light distribution illustratedin FIG. 4A or 4J where the concentric circles mark the magnitude ofintensity (candelas: lumens/steradian), and the lines extending radiallyfrom the center mark the angle of the exiting light with 0° pointingstraight down, 90° to the right and 180° straight up. Any desired lightdistribution may be realized, however.

In an embodiment, extraction features 14 form an outwardly extendingprotrusion as shown in FIG. 4D. The use of such an extraction feature 14limits the distribution of light to either an upward or downwarddirection depending upon which surface of the waveguide body 12, theprotrusions extend from. For example, an extraction feature 14 comprisedof an outwardly extending protrusion, such as one in the shape of adome, located on the upper surface of the waveguide body 12 as shown inFIG. 4D would only allow light to emit in an upward direction. Theopposite would be true if the outwardly protruding extraction featureswere featured on the lower surface of the waveguide body 12. Theseextraction features 14 are particularly useful when combined with thecoupling features discussed above.

In an embodiment, the light produced from the LED 26 is reflected from aceiling in an illuminance maximum to minimum ratio of no greater thanabout 4:1. More preferably, the light is reflected from the ceiling inan illuminance maximum to minimum ratio between about 1:1 to about 3:1.Most preferably, the light is reflected in an illuminance maximum tominimum ratio of no greater than about 2:1.

The illuminance obtained for the disclosed luminaire is such that, inone embodiment, that use of the luminaire can result in a spacingcriteria of about 1:3. In other words, a series of luminaires 10 couldeach be mounted 10 feet apart at a height of 7 feet above a surface tobe illuminated and still achieve an acceptable level of luminance. Uplighting spacing may range from spacing criteria of 1:16 or lower. Inother words, luminaires mounted 16 feet apart at a distance of 1 footfrom the ceiling will still achieve an acceptable level of illuminanceand uniformity. The illustrated embodiment has upward spacing criteriaof 1:10 or less. Down light spacing may range from spacing criteria of1:2 or lower. That is, at 16 feet apart, luminaries may be mounted 8feet from the task surface and deliver the acceptable level ofilluminance and uniformity. In an embodiment, the luminaire may havespacing criteria of 1:3 or less.

FIGS. 5A-5C, 10, 29, and 30 illustrate another embodiment as assembledinto a complete luminaire 60 suspended from a ceiling 62. A waveguidebody 64 is disposed between end caps 66A, 66B that are, in turn, securedto a housing 68. The housing 68 encloses a driver circuit, although thedriver circuit may be disposed at another location. Also, the housing 68may be made of a thermally conductive material, such as aluminum, andmay include heat dissipating structures 70 that radiate heat away fromthe driver circuit components. The housing 68 may be suspended bybrackets 72 and wire rope (i.e., aircraft cable) 74 from appropriateceiling mounting structures, as is conventional. The luminaire 60 mayreceive electrical power via an electrical connection cord 76.

The waveguide body 64 may be oriented in any direction (e.g.,horizontally, vertically, or diagonally). As seen in FIGS. 5B and 5C,the waveguide body 64 is inverted (i.e., flipped over) relative to thewaveguide body 12. Thus, a cavity 82 similar or identical to the cavity29 of a coupling portion 84 that is similar or identical to the couplingportion 24 is disposed above a V-shaped curved surface 86 similar oridentical to the V-shaped surface 46. As in the previous embodiment, theV-shaped surface may be smooth and uncoated, or may be coated with aspecular material or a specular reflective body may disposed adjacentand abutting the V-shaped surface 86 as in the previous embodiment. LEDelement(s) (FIG. 5C) 90 mounted on a substrate 92 may be securedrelative to the waveguide body 64 such that the LED element(s) extendinto the cavity 82. The waveguide body 64 otherwise differs from thewaveguide body 12 in that side sections 90, 92 corresponding to the sidesections 20, 22 are disposed substantially 180 degrees relative to oneanother, extraction features (not shown) similar or identical to any ofthe extraction features 14 disclosed herein are disposed in surfaces 96adjacent the coupling portion 84, and surfaces 98 opposite the surfaces96 have a greater lateral extent than the surfaces 96. The surfaces 96are preferably smooth, although such surfaces may be textured as notedwith respect to the surfaces 32.

As shown in the various embodiments of the Figures, the lower surfaces32 of the waveguide body 12 or 64 may be disposed at any angle Arelative to an axis B (FIG. 4) lying in a plane normal to thelongitudinal axis L and bisecting the coupling portion 24. Morepreferably, this angle A is between about 45° and about 135° (see, e.g.,FIGS. 11-14B). In another embodiment, the lower surface 32 is disposedat an angle A of between about 70° and about 90° relative to the axis B.In the embodiment illustrated in FIGS. 1-4, the lower surface 32 isdisposed at an angle A of about 85° relative to the axis B.

FIGS. 15A and 15B illustrate an embodiment in which the side sections20, 22 are disposed at different angles, and hence, the embodiment isasymmetric. More particularly, lower surfaces 32-1 and 32-2 of the sidesections 20, 22, respectively, form angles C and D, respectively, withrespect to lines parallel to the axis B. In the preferred embodiment,the angles C and D are about 85 degrees and about 135 degrees,respectively, although these angles may have any magnitude. Theembodiment of FIGS. 15A and 15B may have particular utility when used ina ceiling-suspended luminaire that is used adjacent an area where a wallmeets the ceiling. In this case, the section 20 may be directed towardthe intersection of the wall and ceiling such that the surface 30illuminates such intersection and the inside of the room, and thesection 22 may be directed away from such intersection to illuminateinner portions of the ceiling and the work spaces inside the room.

Referring next to FIGS. 16A and 16B, the waveguide body may be partiallyor fully curved to define a curved longitudinal axis L. For example,FIG. 16A illustrates a waveguide body 12A that is partially curved aboutitself, but which is otherwise identical to the waveguide body 12 of anyof the embodiments disclosed herein. The embodiment of FIG. 16A isillustrated as being curved 180 degrees, although the waveguide body maybe curved any other arcuate extent, as desired. FIG. 16B illustrates anembodiment where a waveguide body 21B is fully curved about and joinedto itself (i.e., the waveguide body is curved 360 degrees) to define acircular longitudinal axis L (not shown) and thereby form a circularcylinder. (It should be noted that FIG. 16A also illustrates thewaveguide body of FIG. 16B in cross section). If desired, either of thewaveguide bodies 12A, 12B may define other than a partial or full circlein a plane that includes the curved longitudinal axis L. Thus, forexample, an ellipse or other shape may be defined. The waveguide body21B may be otherwise identical to any of the embodiments disclosedherein and may be used in a luminaire. In such a case LED elements 26may be disposed on a curved substrate 27 wherein the latter is securedto the waveguide body 12A, 12B in any suitable fashion such that the LEDelements 26 extend into the cavity 29 defined by the surfaces 44.

FIGS. 17A-20 and 23A-25D illustrate still further embodiments ofwaveguides that utilize the coupling portion 24 and the V-shaped surface46. (As in the case of FIGS. 16 and 16B, FIGS. 17A and 18A not onlyillustrate alternative embodiments, but also show the embodiments ofFIGS. 17B and 18B, respectively). The embodiments of these Figures aresymmetric about a plane P (seen in FIGS. 17A and 17B) passing throughthe centers of the coupling sections and have a coupling portion 24 oflimited size that can accommodate one or at most several LED elements.FIGS. 17A and 17B illustrate half and full circular waveguide bodies12C, 12D, respectively, whereas FIGS. 18A and 18B depict half and fullsquare waveguide bodies 12E, 12F, respectively. In the illustratedembodiments, the waveguide bodies 12C-12F have cross-sectional shapessimilar or identical to the embodiments of FIGS. 1-4, although any ofthese embodiments may have a different cross-sectional shape, ifdesired. Other similar shapes are also possible, such as quartercircular or quarter square shapes, or shapes that are other thancircular or square.

The alternate embodiments distribute light in the fashion noted inconnection with FIGS. 1-3, and may be used in any luminaire, for exampleas disclosed herein, with suitable modifications as may be necessary ordesirable to accommodate the different waveguide body shape. Forexample, any of the waveguide bodies disclosed herein may be used in theluminaire 60.

FIGS. 1, 2, and 2A also disclose a waveguide body 12 having a centralsection 18 and a first and a second separate side sections 20, 22 thatextend away from the central section 18 along first and seconddirections, respectively. The central section 18 includes a couplingportion 24 located in the central section 18.

In an embodiment, the waveguide body 12 includes a plurality of lightextraction features 14 that extract out of the side sections 20, 22 ofthe waveguide body 12, emitted light generated by an LED light sourceproximal to the waveguide body 12. In another embodiment, each of thefirst and the second side sections 20, 22 has an upper and a lowersurface 30, 32 and a first end 34 proximal to the coupling portion 24and a second end 20A, 22A distal to the coupling portion 24. The firstend 34 has a first thickness T1, the second end has a second thicknessT2, and the first thickness T1 is greater than the second thickness T2.In a particular embodiment, for example, the first thickness T1 is nogreater than about 6 millimeters and the second thickness T2 is no lessthan about 2 millimeters.

In still another embodiment, the coupling portion 24 of the waveguidebody 12 curves upward towards the second end 20A.

In an embodiment, the upper surface 30 of the waveguide body 12 istextured. In a more particular embodiment, each of the plurality oflight extraction features 14 is defined by a first surface 38, and anintermediate surface 40 extends from the first surface 38 to a secondsurface 42, as shown in FIGS. 4B, 4C, 4E, and 4G. All or some of theintermediate surfaces 40 may be planar or curved with each intermediatesurface 40 having a curve of constant radius. In the latter case thesurface 40 is preferably, although not necessarily, convex in crosssection as seen in FIG. 4C. In some embodiments, the surface 40 mayinclude a planar portion as well as a curved portion as shown in FIG.4E. In other embodiments, all or some of the intermediate surfaces 40may be scalloped as shown in FIGS. 4G-4I, in combination with the planaror constant radius curvature noted above. Additionally, all or some ofthe intermediate surfaces 40 may be textured while both or one of thesurfaces 30, 42 are smooth, as seen in FIGS. 4E and 4G. Such texturingmay be accomplished by cutting the surface with a polycrystallinediamond, or by any other suitable means. Surfaces 40 and/or extractionfeatures 14 may be molded, embossed, or otherwise formed in one or bothof the upper and lower surfaces 30, 32 of the waveguide 12.Alternatively, or in addition to, a film (not shown) includingextraction features may be adhered, laminated, or otherwise secured toone or both of the upper and lower surfaces 30, 32 to effectuate lightextraction.

In the embodiments shown in FIGS. 4E, 4F, 4G, and 4H, the surface 40disclosed herein may have the dimensions noted in the following table.It should be noted that the dimensions in the following table asexemplary only and not limiting:

TABLE 3 NOMINAL DIMENSION (Millimeters - unless otherwise specified)FIG. 4F H 0.05 I   45 degrees J 0.005 (radius of curvature) FIG. 4H K0.340 L 27.5 degrees M 0.175 (radius of curvature) FIG. 4I N 37.5degrees P 0.050

In another embodiment, as seen in FIGS. 7 and 8, the intermediatesurfaces 40 are planar, and the intermediate surfaces 40 are allparallel to one another, although the surfaces 40 need not all be planaror parallel. In another embodiment, the intermediate surfaces 40 areparallel to one another and are disposed at non-zero angles with respectto associated first and second surfaces 38, 40. The angle between eachintermediate surface 40 and a line tangent to an adjacent associatedsurface 38 or 42 where the surface 38 or 42 meets the surface 40 may berelatively steep (for example, as seen in FIG. 7) or may be relativelyshallow (e.g., as seen in FIG. 8). This angle (or any other relatedangle, such as the angle between the intermediate surface 40 and a linetangent to an adjacent associated surface 42 where the surface 42 meetsthe surface 40) and the size of each intermediate surface 40 affect theoutput distribution of light from the waveguide body 12.

In a more particular version of this embodiment, the first surface 38 isdisplaced from the second surface 42 by a particular distance and all ofthe distances between the first and the second surface of each of theplurality of light extraction features are equal. In a still moreparticular version of this embodiment, the intermediate surface 40 ofeach step of each of the plurality of extraction features 14 is angledat the same angle.

In one embodiment, the lower surface 32 of the first and the second sidesections 20, 22 of the waveguide body 12 are textured. In a particularversion of this embodiment, the lower surface 32 includes a plurality ofextraction features 14, as discussed above.

As shown in FIG. 3, the coupling portion 24 has a concave first surface44 defining the cavity 29, and a curved V-shaped second surface 46disposed opposite the concave first surface 44. The concave surface 44may be textured so as to allow for better color mixing of the light. Inone embodiment, the V-shaped second surface 46 is smooth and uncoated.In still another embodiment, the V-shaped second surface 46 may be atextured surface and, in a more particular embodiment, an optional layerof specular material 48 may be disposed on the V-shaped second surface46, as shown in FIG. 6.

The concave first surface 44 may include both a curved and linearportion, as shown as 102 and 108 in FIG. 21. Also, the surface of thecentral section 18 opposite the V-shaped second surface 46 may be curvedin a gentle, parabolic manner as shown, for example in FIGS. 13A-15B and21-22, in order to aid in collimating the reflected rays as the greaterthe curvature, the more collimated the rays. Referring to FIG. 21, thefirst surface 44 includes curved and linear portions 102 a, 108 aopposite respective curved and linear portions 102 b, 108 b. Suchsurfaces 102 a, 108 a and respective surfaces 102 b, 108 b may be mirrorimages of one another or have different geometries.

In the embodiments shown in FIGS. 30 and 30A, the waveguide 12 disclosedherein may have the dimensions noted in the following table. It shouldbe noted that the dimensions in the following table as exemplary onlyand not limiting.

TABLE 4 NOMINAL DIMENSION (Millimeters - unless FIG. 30A otherwisespecified) AB 563.355 AC 66.338 AD 1.956 AE 2.850 AF 5.60 AG 0.20 AH 7.0AI 3.965

In yet another embodiment, the waveguide body 12 may be made of atransparent acrylic.

Also disclosed is a coupling optic 100 for a waveguide body 12. As shownin FIG. 21, the coupling optic 100 includes a first coupling section 102disposed in an input region 104 of the coupling optic 100, a firstreflection portion 106 remote from the input region 104 and adapted toreflect light entering the first coupling section 102 into the waveguidebody 12, and a second coupling section 108 disposed at the input region104 and distinct from the first coupling section 102 and adapted torefract light entering the second coupling section 102 directly into thewaveguide body 12.

In an embodiment, the coupling optic 100 has a first surface 110 thatcurves outward from a center of the coupling portion 24, and a secondsurface 112 that curves outward from the center of the coupling portion24 wherein the second surface 112 is opposite the first surface 110. Inone embodiment, both or one of the first and second surfaces 110, 112may be parabolic in shape and centered on the light source 26. Inanother embodiment, one or both of the first and second surfaces 110,112 may be “free formed” in that it is specifically designed to controlthe angles of the light rays or the spread of the collimated group ofrays that are directed through the waveguide 12. In other embodiments,one or both of the first and second surfaces 110, 112 may be acombination of a parabolic and free formed shape. Additionally,referring to FIG. 21, the coupling optic 100 includes third and fourthsurfaces 110 b, 112 b opposite respective first and second surfaces 110a, 112 a. First and third surfaces 110 a, 110 b may be mirror images ofeach other or have different shapes. Similarly, second and fourthsurfaces 112 a, 112 b may be mirror images of each other or havedifferent shapes. The coupling optic 100 also has an end 114 distal tothe center of the coupling portion 24, and a waveguide 12 is attached tothe end 114. In a more specific version of the embodiment, the ends 114of the first and second surfaces 110, 112 define a line that isapproximately perpendicular to the first surface 110 and the secondsurface 112. Each of the first and second surfaces 110, 112 may betextured surfaces.

When in operation, the primarily lambertian distribution of lightemitted from the LED element(s) 26 travels through the first couplingsection 102 where it then strikes the first reflection portion 106. Thesurface of the first coupling section 102 redirects the light by TIRtoward the second surface 112 or into the waveguide 12 as one set ofsubstantially collimated or parallel rays of light that bounce due tototal internal reflection between the upper and lower surfaces of thewaveguide 12 until such rays exceed the critical angle of the materialof the waveguide body 12 and escape.

FIGS. 28 and 28A illustrate a waveguide 200 comprising a waveguide body202 and a series of LEDs 26 of any suitable type, including the typesdisclosed herein, disposed on a surface 204 of a substrate 206. Thesurface 204 may be coated with a specular or white reflective surface.The waveguide body 202 includes a coupling portion 208 similar oridentical to the coupling portion 24 disclosed above. The side sectionsof previous embodiments are replaced by a single light emitting section204 that may include stepped (or other shaped) extraction features, asdisclosed previously. As in other embodiments light rays may be arrangedinto groups wherein the light rays of each group travel at angles withina desired range of one another, within the TIR limits of the waveguidebody material, so that the light rays TIR at least once within thewaveguide body.

FIGS. 31-44 illustrate yet another embodiment of a luminaire 360suspended from a ceiling. The luminaire 360 includes one or moreluminaire sections that are assembled together in end to end fashion asnoted in greater detail hereinafter. The luminaire sections arepreferably identical (with the exception of end caps as described below)and, while the drawings illustrate the use of two sections, any numberof luminaire sections may be joined together to obtain a luminaire ofdesired length, with the only limitation on the number of sections beingthe electrical power available to energize the sections. Also, while thedrawings illustrate that the luminaire 360 is suspended from a ceilingat two ends 362, 364 thereof and that electrical power is supplied tothe luminaire 360 at the end 362, it should be noted that the luminaire360 may be suspended from or mounted to any surface other than aceiling, including a vertical or horizontal or inclined surface, andthat the luminaire may have at least one, and preferably more than onesuspension or mounting points located at the ends and/or intermediateportions of the luminaire 360 and/or may receive power at more than oneportion thereof, as necessary or desirable.

Referring specifically to FIGS. 31-33, the illustrated luminaire 360includes first and second luminaire sections 370, 372 that are joinedtogether at an intermediate coupling section 374. First and secondsuspension members 376, 378 include mounting plates 380, 382,respectively, adapted to be mounted to ceiling junction boxes (notshown) and aircraft cables 384, 386, respectively, that are secured asdescribed hereinafter to the luminaire 360. The first luminaire section370 includes a power input end cap 390 disposed at the end 362 andadapted to receive electrical power via a cord 392. A further end cap394 is disposed at the end 364.

Referring to FIGS. 34-38 and 38A, the section 370 is hereinafterdescribed in detail, it being understood that the section 372 isidentical thereto. The section 370 includes a waveguide body 400, afirst hollow structural member 402 disposed on a first side of thewaveguide body 400, and a second hollow structural member 404 disposedon a second side of the waveguide body opposite the first side.Preferably, each of the first and second structural members is made ofextruded aluminum, although any suitable material or combinations ofmaterials could be used. The first and second structural members 402,404 and the waveguide body 400 are secured to one another by one or morefasteners, such as a bolt 406 (FIG. 39) that extends through a bore 408in the second structural member 404, and further extends through alignedbores 410, 412 in the waveguide body 400 and the first structural member402 (the bore 412 is visible in FIG. 38A). A nut 414 is threaded ontothe bolt 406.

A plurality of LEDs 420 as described in connection with the precedingembodiments is disposed on a circuit board 422 carried by the secondstructural member 404 (FIGS. 38 and 39). Referring specifically to FIG.38, the LEDs 420 extend into the coupling cavity 424 of the waveguidebody 400. The waveguide body 400 is similar or identical to any of thewaveguide bodies described hereinabove. Two optional elongate reflectivestrips 430, 432 (seen in FIGS. 38, 38A, and 39) are disposed betweenfirst and second side flanges 434, 436, respectively, and bottomsurfaces 438, 440, respectively, of the waveguide body 400. Thereflective strips 430, 432 obscure the LEDs 420 so that the LEDs 420cannot be directly observed.

The first structural member 402 includes an opening 440 (FIGS. 38A, 39)that permits access to the hollow interior of the member 402. A housing442 that contains one or more components of the circuit C and/or thecircuit LC described above is disposed within the first structuralmember 402 and the housing 442 is secured therein in any suitablefashion. One or more communication components forming a part of thelight control circuit LC, such as an RF antenna 443 (FIG. 38A) thatsenses RF energy, may be disposed above the housing 402 and a cover 444is secured by, for example, a snap fit, in the opening 440 above thehousing 442 and the communication components. The communicationcomponents may be included, for example, to allow the luminaire 360 tocommunicate with an external wireless controller, such as disclosed inU.S. patent application Ser. No. 13/782,040, filed Mar. 1, 2013,entitled “Lighting Fixture for Distributed Control” or U.S. ProvisionalPatent Application No. 61/932,058, filed Jan. 27, 2014, entitled“Enhanced Network Lighting” both owned by the assignee of the presentapplication and the disclosures of which are incorporated by referenceherein. More generally, the control circuit LC includes at least one ofa network component, an RF component, a control component, and a sensor.The cover 444 may be made of plastic or any other non-electricallyconductive material that allows transmission of electromagnetic wavestherethrough.

Referring to FIGS. 39-44, a male junction member 450 is secured to afirst end 370 a of the section 370 by fasteners in the form of screws452 (FIG. 39) that threadedly engage cylindrical surfaces 454, 455formed in the first structural member 402 and the second structuralmember 404, respectively. A female junction member 456 is secured to asecond end 372 b of the section 372 by further fasteners in the form ofscrews 458 that are threaded into the cylindrical surfaces 454, 455 (thesurfaces 454, 455 are visible in FIG. 38 and extend the full length ofthe section 370, but need not do so, in which case the fasteners mayengage other surfaces, as should be evident). Complementary first andsecond electrical connectors 460, 462 are electrically coupled toconductors in the form of wires 464 that extend into the firststructural member 402 and interconnect with components of the circuit Cand further extend into the second structural member 404 and connect tothe circuit board 422. The first electrical connector 460 is securedwithin an opening 466 (FIG. 35) extending through the male junctionmember 450 by any suitable means, such as a snap fit. Similarly, thesecond electrical connector 462 is secured within an opening 468 (FIG.36) extending through the female junction member 456 by any suitablemeans, such as a snap fit.

Referring next to FIGS. 39-44, a clamping member 470 (FIGS. 39-41, 43,and 44) includes an insulator plate 472 that is secured by bolts orother fasteners 472 a to threaded bores, thereby capturing a circuitboard 473 a and one or more optional sensors, such as a knob-shapedsensor 473 b, inside an opening 474 (FIGS. 39, 39A, 43, and 44). Thecircuit board 473 a and the sensor 473 b comprise an optional part ofthe control circuit LC and provide an indication of ambient lightinglevels thereto. The insulator plate 472 electrically isolates thecircuit board 473 a. First and second clamping fasteners 475 a, 475 bextend through bores 476 a, 476 b in side portions 478 a, 478 b of themale junction member 450 and into threaded bosses 480 a, 480 b (FIGS. 39and 39A) of the clamping member 470. The luminaire section 370, as wellas other sections, such as the section 372, are preferably (although notnecessarily) shipped with the clamping fasteners 475 a, 475 b onlypartially threaded into the threaded bosses 480 a, 480 b to facilitateassembly by an end user.

FIGS. 40-42 illustrate the process of assembling the sections 370, 372.FIG. 40 illustrates the male junction member 450 disposed on the end 370a of the section 370 and the female junction member 456 disposed on anend 372 b of the section 372. Prior to assembly, the clamping member 470is loosely disposed on the male junction member 450 due to the partialthreading of the clamping fasteners 475 a, 475 b in the threaded bosses480 a, 480 b, respectively. (The clamping fasteners 475 are partiallyunthreaded out of the bosses 480 if the fasteners are initially fullythreaded therein so that the clamping member 470 is allowed to move awayfrom the male junction member 450 before assembly.) Referring next toFIG. 41, the sections 370 and 372 are then aligned as shown and thesections 370 and 372 are then brought together and mated as seen in FIG.42 such that two compression surfaces 482 and 484 (FIGS. 40 and 41) ofthe male junction member 450 and the female junction member 456,respectively, contact one another and such that locating pins 486 a-486c are received within bores 488 a-488 c, respectively. The mating of thesections 370 and 372 causes the electrical connectors 460, 462 in thesections 370, 372 to engage with one another, and thereby cause theconductors 464 to become interconnected so that electrical power cantransfer between the sections 370, 372.

As seen in FIGS. 33, 34 and 39A, tightening the clamping fasteners 475a, 475 b after mating of the sections 370, 372 causes upwardly facingprojections 490 a-490 d of the clamping member 470 to move upward asseen in the Figures and enter recesses 492 a-492 d in lower surfaces494, 495 of the male and female junction members 450, 456 (the recesses492 c, 492 d are not visible, but are mirror images of the recesses 492a, 492 b, respectively, and are disposed on either side of the bore 476b). Continued tightening of the clamping fasteners 475 a, 475 b causesangled surfaces 496 a-496 d of the projections 490 a-490 d to engage andslide upwards relative to angled surfaces 497 a-497 d that define therecesses 492 a-492 d. The angled surfaces 496 a-496 d and the angledsurfaces 497 a-497 d are inclined at angles relative to a center line498 of the clamping member 470 so that tightening of the clampingfasteners 475 a, 475 b results in placement of the clamping member 470in tension and placement of the surfaces 482, 484 in compression.Additional surfaces 500, 502 of the male junction member 450 andsurfaces 504, 506 of the female junction member 456 (FIGS. 40-42) arealso placed in compression as a result of tightening of the clampingfasteners 475 a, 475 b. The tolerances of the various parts and thedegree to which the fasteners 475 can be threaded into the bosses 480are such that the relative placement of the sections 370 and 372 can beadjusted. For example, tightening of one or both of the fasteners 475 a,475 b to particular positions in the bosses 480 may result insubstantial horizontal alignment of the sections 370, 372. Tightening toother position in the bosses 480 may result in a horizontal V-shape orhorizontal inverted V-shape disposition of the sections 370, 372.Differential tightening of the fasteners 475 a, 475 b in the bosses 480may result in a side to side alignment or misalignment of the sections370, 372. This adjustability permits installation in situations wherevertical and side to side section placement must be controlled. Also,the locations of the locating pins 486 and bores 488, the surfaces 482,484, 500, 502, 504, and 506 are such that substantial resistance againstdeflection forces in multiple planes is provided. The sections 370, 372are thereby rigidly locked together in multiple planes, and sagging atsuch location is minimized, in turn minimizing overall sagging of theluminaire 360.

Referring again to FIGS. 31-33, the power input end cap 390 disposed atthe end 362 at least partially encloses the coupling section of thewaveguide body and includes a mating electrical connector (not shown)identical to the electrical connector 460 wherein the connector in thecap 390 engages with the electrical connector 462 in the end 370 b toreceive electrical power via the cord 392. In the illustrated embodimentthe further end cap 394 further encloses the coupling section of thewaveguide body and is disposed at the end 372 a of the section 372 andmay include an electrical connector (also not shown) identical to theconnector 462 that engages the connector 460 disposed at the end 372 a.The electrical connector 512 in the end cap 394 may complete a circuitas required to supply power to the LEDs 420. Alternatively, ifelectrical connection(s) are not required at the end cap 394, theelectrical connector therein may be omitted.

As seen in FIG. 38, the first structural member 402 includes twoelongate side slots 520, 522 that are adapted to receive and retaintherein mounting apparatus including apertured tabs 524 a-524 d (FIGS.31-33, 35, 36, and 39). As seen in FIGS. 31-33, ends of main sections384 a, 386 a of the aircraft cables 384, 386 may be secured to tubularmembers 526, 528 and auxiliary sections 384 b, 386 b of aircraft cables384, 386 extend through aligned holes in the walls of the tubularmembers 526, 528 and are secured to the apertured tabs 524 a-524 d tomount the luminaire 360.

In the preferred embodiment, each of the sections 370, 372 is 4 feet inlength, although each section may be of any other length. Sections ofthe preferred size are easy to transport, do not noticeably sag, and arereadily manufactured and handled. The shapes of the first and secondstructural members are such that the members do not significantlyobstruct emitted light and are light and strong. Strength is furtherenhanced by the concave shape of the lower portion of the secondstructural member, which also adds aesthetic appeal and further allowssections to be nested together during shipment. The side slots 520, 522may serve as a wire routing feature so that wire visibility isminimized. The side slots 520, 522 can also accommodate alternativemounting devices as desired, so that the luminaire 360 can be mounted inother orientations, and/or to other structures.

Preferably, the angled surfaces 496 a-496 d have a length between about4.82 mm and about 4.98 mm, and, more preferably between about 4.85 mmand about 4.95 mm. Further, the angled surfaces 496 a-496 d are disposedat angles between about 29 degrees and about 31 degrees, and, morepreferably between about 29.5 degrees and about 30.5 degrees relative tothe center line 498. Still further, the angled surfaces 497 a-497 dpreferably have a length between about 2.12 mm and about 2.28 mm, and,more preferably between about 2.15 mm and about 2.25 mm. Further, theangled surfaces 497 a-497 d are disposed at angles between about 34degrees and about 36 degrees, and, more preferably between about 34.5degrees and about 35.5 degrees relative to the center line 498.

The present embodiment has an aspect ratio (i.e., the ratio of luminairewidth to height excluding mounting components) of at least about 1.0,and more preferably at least about 2.0, and most preferably about 4.8.Also, the overall width of the mechanical components (excluding mountingcomponents and optical components) as a ratio of the overall width ofthe luminaire (excluding mounting components) is desirably low,preferably no more than about 30 percent, more preferably no more thanabout 20 percent, and most preferably about 14.5 percent. Further, muchof the light distribution is directed upwardly toward a ceiling, and thelarge optical component size results in low luminance and, therefore,less objectionable glare. Still further, the illumination of the opticalsurface of the luminaire is desirably close to the appearance of aceiling illuminated by the luminaire, when viewed from below. In fact,luminance variations of about 6:1 or less are preferable, with luminancevariations of less than about 3:1 being more preferable and luminancevariations of less than about 2:1 being most preferable such thatextreme observed variations are minimized. In addition, the use of LEDsresults in a low power luminaire.

It should be noted that other alternatives are possible. For example,LEDs may be disposed on the bottom of the luminaire, but may not bedisposed in a structural member, such as a housing, and the electronicsincluding the power circuit C and/or the light control circuit LC may bedisposed above the luminaire within or outside of a structural member,such as in or outside a housing. Alternatively, one or more componentsof the circuits C and/or LC and/or one or more other components may bedisposed in the second structural member (see FIGS. 38, 38A) and one ormore LEDs may be disposed in the first structural member (in which casethe waveguide body may be inverted), or all of the components of thecircuits C, LC and all of the LEDs may be disposed in one of the firstand second structural members, in which case the other of the first andsecond structural members may be omitted. The luminaire may be suspendedfrom a top structural member, such as a top housing, and/or above abottom structural member, such as a housing, or may be suspended fromany other component or structure.

INDUSTRIAL APPLICABILITY

In summary, it has been found that when using a single color ormulticolor LED element in a luminaire, it is desirable to mix the lightoutput developed by the LEDs thoroughly so that the intensity and/orcolor appearance emitted by the luminaire is uniform. When the LEDelement is used with a waveguide, opportunities have been found to existto accomplish such mixing during the light coupling and light guiding ordistributing functions. Specifically, bending the light rays byrefraction can result in improvement in mixing. In such a case, thisrefractive bending can be accomplished by providing interfaces in thewaveguide between materials having different indices of refraction.These interfaces may define coupling features where light developed bythe LED elements enters the waveguide and/or light redirection featuresat portions intermediate the coupling features and waveguide extractionfeatures or areas where light is otherwise extracted (such as by bends)from the waveguide. It has further been found that directing light intoa wide range of refraction angles enhances light mixing. Because theangle A_(r) of a refracted light ray is a function of the angle A_(i)between the incident light ray and the interface surface struck by theincident light ray (with refractive angle A_(r) increasing as A_(i)approaches zero, i.e., when the incident light ray approaches a parallelcondition with respect to the interface surface), a wide range ofrefracted light ray angles can be obtained by configuring the interfacesurfaces to include a wide range of angles relative to the incidentlight rays. This, in turn, means that the interfaces could include asignificant extent of interface surfaces that are nearly parallel to theincident light rays, as well as other surfaces disposed at other anglesto the incident light rays. Overall waveguide shapes and couplingfeature and redirection feature shapes such as curved (including convex,concave, and combinations of convex and concave surfaces), planar,non-planar, tapered, segmented, continuous or discontinuous surfaces,regular or irregular shaped surfaces, symmetric or asymmetric shapes,etc. can be used, it being understood that, in general, light mixing(consistent with the necessary control over light extraction) can befurther improved by providing an increased number of interface surfacesand/or more complex interface shapes in the light path. Also, thespacing of coupling features and light redirection features affect thedegree of mixing. In some embodiments a single light coupling featureand/or a single light redirection feature may be sufficient toaccomplish a desired degree of light mixing. In other embodiments,multiple coupling features and/or multiple light redirection featuresmight be used to realize a desired degree of mixing. In either event,the shapes of multiple coupling features or multiple redirectionfeatures may be simple or complex, they may be the same shape or ofdifferent shapes, they may be equally or unequally spaced, ordistributed randomly or in one or more arrays (which may themselves beequally or unequally spaced, the same or different size and/or shape,etc.) Further, the interfaces may be disposed in a symmetric orasymmetric pattern in the waveguide, the waveguide itself may besymmetric or asymmetric, the waveguide may develop a light distributionthat is symmetric, asymmetric, centered or non-centered with respect tothe waveguide, the light distribution may be on-axis (i.e., normal to aface of the waveguide) or off-axis (i.e., other than normal with respectto the waveguide face), single or split-beam, etc.

Still further, one or more coupling features or redirection features, orboth, may be disposed anywhere inside the waveguide, at any outsidesurface of the waveguide, such as an edge surface or major face of thewaveguide, and/or at locations extending over more than one surface orportion of the waveguide. Where a coupling or light redirection featureis disposed inside the waveguide, the feature may be disposed in or bedefined by a cavity extending fully through the waveguide or in or by acavity that does not extend fully through the waveguide (e.g., in ablind bore or in a cavity fully enclosed by the material of thewaveguide). Also, the waveguide of any of the embodiments disclosedherein may be planar, non-planar, irregular-shaped, curved, othershapes, suspended, etc.

While specific coupling feature and light redirection feature parametersincluding shapes, sizes, locations, orientations relative to a lightsource, materials, etc. are disclosed as embodiments herein, the presentinvention is not limited to the disclosed embodiments, inasmuch asvarious combinations and all permutations of such parameters are alsospecifically contemplated herein. Thus, any one of the couplingcavities, plug members, LED elements, masking element(s), redirectionfeatures, extraction features, etc. as described herein may be used in aluminaire, either alone or in combination with one or more additionalelements, or in varying combination(s) to obtain light mixing and/or adesired light output distribution. More specifically, any of thefeatures described and/or claimed in U.S. patent application Ser. No.13/842,521, U.S. patent application Ser. No. 13/839,949, U.S. patentapplication Ser. No. 13/841,074, filed Mar. 15, 2013, entitled “OpticalWaveguide Body”, U.S. patent application Ser. No. 13/840,563, U.S.patent application Ser. No. 14/101,086, filed Dec. 9, 2013, entitled“Optical Waveguides and Luminaires Incorporating Same” by Keller et al.,U.S. patent application Ser. No. 14/101,099, filed Dec. 9, 2013,entitled “Optical Waveguide Assembly and Light Engine Including Same” byYuan et al., U.S. patent application Ser. No. 14/101,132, filed Dec. 9,2013, entitled “Waveguide Bodies Including Redirection Features andMethods of Producing Same” by Tarsa, U.S. patent application Ser. No.14/101,147, filed Dec. 9, 2013, entitled “Luminaires Using WaveguideBodies and Optical Elements” by Keller et al., U.S. patent applicationSer. No. 14/101,129, filed Dec. 9, 2013, entitled “Simplified LowProfile Module with Light Guide for Pendant, Surface Mount, Wall Mount,and Stand Alone Luminaires” by Tarsa et al., U.S. patent applicationSer. No. 14/101,051, filed Dec. 9, 2013, entitled “Optical Waveguide andLamp Including Same” by Yuan et al. and International Application No.PCT/US14/13931, filed Jan. 30, 2014, entitled “Optical Waveguides andLuminaires Incorporating Same”, incorporated by reference herein andowned by the assignee of the present application may be used in thedevices disclosed herein. Thus, for example, any of the waveguides orluminaires disclosed herein may include one or more coupling features oroptics, a modified LED arrangement, one or more light redirectionfeatures, one or more extraction features, and/or particular waveguideor overall luminaire shapes and/or configurations as disclosed in suchapplications, as necessary or desirable. Other luminaire and waveguideform factors than those disclosed herein are also contemplated.

The coupling features disclosed herein efficiently couple light into thewaveguide, and the redirection features uniformly mix light within thewaveguide and the light is thus conditioned for uniform extraction outof the waveguide. At least some of the luminaires disclosed herein areparticularly adapted for use in installations, such as, replacement orretrofit lamps (e.g., LED PAR bulbs), outdoor products (e.g.,streetlights, high-bay lights, canopy lights), and indoor products(e.g., downlights, troffers, a lay-in or drop-in application, a surfacemount application onto a wall or ceiling, etc.) preferably requiring atotal luminaire output of at least about 800 lumens or greater, and,more preferably, a total luminaire output of at least about 3000 lumens,and most preferably a total lumen output of about 10,000 lumens.Further, the luminaires disclosed herein preferably have a colortemperature of between about 2500 degrees Kelvin and about 6200 degreesKelvin, and more preferably between about 2500 degrees Kelvin and about5000 degrees Kelvin, and most preferably about 2700 degrees Kelvin.Also, at least some of the luminaires disclosed herein preferablyexhibit an efficacy of at least about 100 lumens per watt, and morepreferably at least about 120 lumens per watt, and further exhibit acoupling efficiency of at least about 92 percent. Further, at least someof the luminaires disclosed herein preferably exhibit an overallefficiency (i.e., light extracted out of the waveguide divided by lightinjected into the waveguide) of at least about 85 percent. A colorrendition index (CRI) of at least about 80 is preferably attained by atleast some of the luminaires disclosed herein, with a CRI of at leastabout 88 being more preferable. A gamut area index (GAI) of at leastabout 65 is achievable. Any desired particular output lightdistribution, such as a butterfly light distribution, could be achieved,including up and down light distributions or up only or down onlydistributions, etc.

When one uses a relatively small light source which emits into a broad(e.g., Lambertian) angular distribution (common for LED-based lightsources), the conservation of etendue, as generally understood in theart, requires an optical system having a large emission area to achievea narrow (collimated) angular light distribution. In the case ofparabolic reflectors, a large optic is thus generally required toachieve high levels of collimation. In order to achieve a large emissionarea in a more compact design, the prior art has relied on the use ofFresnel lenses, which utilize refractive optical surfaces to direct andcollimate the light. Fresnel lenses, however, are generally planar innature, and are therefore not well suited to re-directing high-anglelight emitted by the source, leading to a loss in optical efficiency. Incontrast, in the present invention, light is coupled into the optic,where primarily TIR is used for re-direction and collimation. Thiscoupling allows the full range of angular emission from the source,including high-angle light, to be re-directed and collimated, resultingin higher optical efficiency in a more compact form factor.

Embodiments disclosed herein are capable of complying with improvedoperational standards as compared to the prior art as follows:

Improved Standards State-of-the Achievable by Present Art StandardsEmbodiments Input (coupling + 90% Almost 95%: improved waveguide)through color mixing, source mixing, and control within the waveguide.Output (extraction) 90% About 95%: improved through extractionefficiency. Total system ~80% About 90%: greater control, many choices

In at least some of the present embodiments, the distribution anddirection of light within the waveguide is better known, and hence,light is controlled and extracted in a more controlled fashion. Instandard optical waveguides, light bounces back and forth through thewaveguide. In the present embodiments, light is extracted as much aspossible over one pass through the waveguide to minimize losses.

In some embodiments, one may wish to control the light rays such that atleast some of the rays are collimated, but in the same or otherembodiments, one may also wish to control other or all of the light raysto increase the angular dispersion thereof so that such light is notcollimated. In some embodiments, one might wish to collimate to narrowranges, while in other cases, one might wish to undertake the opposite.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar reference in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Recitation of ranges of values herein are merely intended toserve as a shorthand method of referring individually to each separatevalue falling within the range, unless otherwise indicated herein, andeach separate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the disclosure and does not pose alimitation on the scope of the disclosure unless otherwise claimed. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential to the practice of the disclosure.

Preferred embodiments of this disclosure are described herein, includingthe best mode known to the inventors for carrying out the disclosure. Itshould be understood that the illustrated embodiments are exemplaryonly, and should not be taken as limiting the scope of the disclosure.

We claim:
 1. A luminaire comprising: an optical element comprising acoupling portion and first and second sections; wherein the couplingportion comprises a concave coupling cavity that extends into thecoupling portion and along a length of the optical element, and asurface located opposite the coupling cavity; wherein a shortestdistance between the surface and the coupling cavity is greater than adepth of the coupling cavity into the coupling portion, and the couplingcavity is configured to receive at least one light emitting diode; andwherein the first and second sections extend away from the couplingportion of the optical element along the length of the coupling cavity,wherein the first section comprises a first thickness closer to thecoupling portion and a second thickness further from the couplingportion, the first thickness is greater than the second thickness, thesecond section comprises a third thickness closer to the couplingportion and a fourth thickness further from the coupling portion, thethird thickness is greater than the fourth thickness, and light isextracted out of extraction features of opposing sides of at least onesection.
 2. The luminaire of claim 1, wherein the surface of thecoupling portion located opposite the coupling cavity comprises firstand second coupling surfaces that are configured to direct light ontofirst and second control surfaces.
 3. The luminaire of claim 2, whereinthe first and second control surfaces are configured to direct lightinto at least one of the first and second sections.
 4. The luminaire ofclaim 3, wherein at least one of the first and second control surfacesis configured to direct light as a collimated ray group.
 5. Theluminaire of claim 2, wherein the first and second control surfacesdefine a V-shape of the surface.
 6. The luminaire of claim 5, whereinthe V-shape of the surface is coated with a specular material.
 7. Theluminaire of claim 1, wherein the extraction features protrude outwardlyfrom the at least one of the first and second sections.
 8. The luminaireof claim 1, wherein the light produced from the at least one lightemitting diode is reflected from a ceiling in an illuminance per unitarea maximum to minimum ratio of about 3:1.
 9. The luminaire of claim 1,wherein the light produced from the at least one light emitting diode isreflected from a ceiling in an illuminance maximum to minimum ratiobetween about 2:1 to 4:1.
 10. The luminaire of claim 1, wherein thelight produced from the at least one light emitting diode is reflectedfrom a ceiling in an illuminance maximum to minimum ratio of no greaterthan about 3:1.
 11. The luminaire of claim 1, wherein the light producedfrom the at least one light emitting diode is reflected from a ceilingin an illuminance maximum to minimum ratio of no less than about 2:1.